V-shaped belt, belt-type transmission, and saddle-type vehicle

ABSTRACT

To enhance the durability of the V-shaped belt by allowing the strength and the heat-radiating property of the resin blocks to stand together at high levels in the V-shaped belt, which has a plurality of resin blocks and endless connecting members connecting the resin blocks. The V-shaped belt includes a plurality of resin blocks arranged in a direction and an endless connecting member that is impacted into the resin blocks and that extends in the arrangement direction of the resin blocks. Depressions are longitudinally and vertically formed in the upside and downside of the front surface and the rear surface of each resin block. The depressions are separated from the connecting member and are also separated from the lateral surfaces of the resin block.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a V-shaped belt, a belt-typetransmission, and a saddle-type vehicle.

2. Description of Related Art

Conventionally, a V-shaped belt having a plurality of blocks and anendless connecting member for connecting the blocks has been used for abelt-type continuously variable transmission fitted to a motor bicycleor the like. As the blocks used for such a V-shaped belt, blocks made ofmetal such as aluminum, blocks obtained by coating a metal moldedmaterial with a resin, or the like have been known.

The V-shaped belt is used by winding itself around sheaves (pulleys)rotating at a high speed or the like. As a result, decrease in weight ofthe V-shaped belt has been required to facilitate the high-speedrotation. Therefore, in order to accomplish the decrease in weight ofthe V-shaped belt, it has been suggested that blocks made of resin orsubstantial resin (hereinafter, referred to as resin blocks) are used asthe blocks (for example, see Japanese Patent JP-A-2002-147553).

The V-shaped belt disclosed in Japanese Patent JP-A-2002-147553 isdescribed with reference to FIGS. 22 and 23. As shown in FIG. 22, theV-shaped belt 100 comprises a number of resin blocks 101 arranged in aline and an endless connecting member 102. As shown in FIG. 23( b), eachresin block 101 has a falling H shape as seen from the front side andgrooves 105 are formed inward in both sides of each resin block 101. Asshown in FIG. 22, the connecting members 102 are impacted into thegrooves 105 of each resin block 101. As a result, the resin blocks 101are connected to each other through the connecting members 102. Theconnecting members 102 include a rubber 103 and cores 104 buried in therubber 103. Although not shown, the V-shaped belt 100 is wound around aprimary sheave and a secondary sheave of a belt-type continuouslyvariable transmission.

A large amount of heat is generated in the V-shaped belt 100 due tofriction with the sheaves. In addition, frictional heat is generatedbetween the resin blocks 101 and the connecting member 102. Internalheat is generated in accordance with the unevenness of the connectingmembers when they are wound around the sheaves and the like.Accordingly, the heat easily increases the temperature of the V-shapedbelt 100.

However, resin is a material having thermal conductivity lower than thatof metal. As a result, in the V-shaped belt 100 employing the resinblocks 101, since heat can easily stay in the resin blocks 101, thetemperatures of the resin blocks 101 and the connecting members 102 areeasily increased. Therefore, the V-shaped belt 100 is not enough fromthe point of view of a heat-proof characteristic.

Therefore, there was suggested a V-shaped belt with an improvedheat-radiating property. In Japanese Patent JP-UM-A-61-97647, it isdisclosed that a V-shaped belt having falling H-shaped resin blocks isprovided with depressions recessed downward in both sides of the topsurface of the resin blocks. In the V-shaped belt, since theheat-radiating area can be enlarged by the depression and the thermallyconductive distance between external air and engaging portions (portionsin which the resin blocks and the connecting members engage with eachother) which is a frictional heat source can be reduced, efficientradiation of the frictional heat is accomplished.

However, in the V-shaped belt disclosed in Japanese PatentJP-UM-A-61-97647, since the depressions recessed downward are formed inthe top surfaces of the resin blocks, the area of both side surfaces ofthe resin blocks which contact the sheaves is reduced. As a result, asufficient contact area cannot be guaranteed between the V-shaped beltand the sheaves, and thus it cannot be said to provide sufficientstrength. Specifically, it is difficult to maintain a high rigidity inthe arrangement direction of the resin blocks (longitudinal rigidity).On the contrary, when the size of the depressions is decreased in orderto maintain sufficient strength, the heat-radiating area is reduced.Accordingly, a sufficient cooling effect cannot be obtained.

In Japanese Patent JP-A-61-286638, it is disclosed that a V-shaped beltis formed by integrally vulcanizing blocks and an endless belt body,clearances are formed between the neighboring blocks, and cooling air isintroduced into the clearances between the blocks. Specifically, aV-shaped belt having falling H-shaped blocks and a V-shaped belt havingblocks obtained by coupling upper blocks and lower blocks each otherwith pins are disclosed in Japanese Patent JP-A-61-286638. In theV-shaped belt having the falling H-shaped blocks, the thickness of bothlateral ends of each block is smaller than that of the center thereof,and thus a clearance is formed between the neighboring blocks at thelateral ends of the block. On the other hand, in the V-shaped belthaving the blocks consisting of the upper blocks and the lower blocks, aclearance is formed not between the neighboring lower blocks but betweenthe neighboring upper blocks.

In the V-shaped belt having the falling H-shaped blocks disclosed inJapanese Patent JP-A-61-286638, since the sufficient contact area cannotbe guaranteed between the sheaves and the V-shaped belt as describedabove, it is difficult to maintain the sufficient strength. In addition,since the clearances between the neighboring blocks reach the belt bodyin the V-shaped belt, the strength of the engaging portions of theblocks with the belt body is insufficient although the blocks and thebelt body are integrally vulcanized.

In the V-shaped belt having the upper blocks and the lower blocksdisclosed in Japanese Patent JP-A-61-286638, the lower blocks contactthe sheaves but no clearance is formed between the neighboring towerblocks. As a result, it is possible to guarantee the sufficient contactarea between the sheaves and the V-shaped belt but it is difficult toobtain a sufficient cooling effect. In the V-shaped belt, some degree ofcooling effect may be obtained from the upper blocks. However, since theupper blocks and the lower blocks are individual members connected toeach other with the pins, the effective cooling of the upper blockscannot necessarily guarantee the cooling of the lower blocks.

As described above, it is difficult to allow the strength and theheat-radiating property of the resin blocks to stand together in theconventional V-shaped belt.

SUMMARY OF THE INVENTION

The present invention is contrived in view of the above-mentionedproblems and it is an object of the present invention to improve thedurability of the V-shaped belt by allowing the strength and theheat-radiating property of the resin blocks at a high level in theV-shaped belt having resin blocks and connecting members.

According to an aspect of the present invention, there is provided aV-shaped belt comprising: a plurality of resin blocks arranged in adirection; and an endless connecting member that extends in thearrangement direction of the resin blocks and that is impacted into theresin blocks to connect the resin blocks, wherein a depression recessedin the arrangement direction of the resin blocks and separated from theconnecting member is formed in each resin block.

In the V-shaped belt, since the depression recessed in the arrangementdirection is formed in each resin block, it is possible to enlarge theheat-radiating area of the resin blocks and to introduce the air betweenthe resin blocks, thereby improving the heat-radiating property. Inaddition, since the depression is separated from the connecting member,the engagement strength between the resin blocks and the connectingmember is not weakened depending upon the shapes of the depression, andthus it is possible to keep the strength of the V-shaped belt high.Therefore, it is possible to allow the strength and the heat-radiatingproperty of the resin blocks to stand together at a high level, therebyimproving the durability of the V-shaped belt.

According to another aspect of the present invention, there is provideda V-shaped belt comprising a plurality of resin blocks arranged in adirection, each resin block having grooves inwardly formed at verticalcenters of both lateral surfaces, and an endless connecting member thatextends in the arrangement direction of the resin blocks and is impactedinto the grooves of the resin blocks to connect the resin blocks,wherein a depression exposed to air is formed at a lateral center ofeach resin block.

The inventors found out that the portion in a so-called falling H-shapedresin block in which heat can easily stay is the center portion, andthus the entire resin block can be efficiently cooled by cooling thecenter portion. In the V-shaped belt, the depression exposed to the airis formed at the center of each falling H-shaped resin block. As aresult, since the portions in which the heat can easily stay can bedirectly cooled, it is possible to obtain a sufficient heat-radiatingproperty without enlarging the depression. Therefore, it is possible toallow the strength and the heat-radiating property of the resin blocksto stand together at a high level, thereby improving the durability ofthe V-shaped belt.

According to another aspect of the present invention, there is provideda V-shaped belt comprising a plurality of resin blocks arranged in adirection, each resin block having grooves inwardly formed at verticalcenters of both lateral surfaces, and an endless connecting member thatextends in the arrangement direction of the resin blocks and is impactedinto the grooves of the resin blocks to connect the resin blocks,wherein a depression exposed to air and separated from both lateralsurfaces of the resin blocks is formed in each resin block.

In the V-shaped belt, since the depression exposed to the air is formedin each resin block, the heat-radiating property is improved. Inaddition, since the depression is separated from both lateral surfacesof each resin block, it is possible to sufficiently secure the contactarea between the resin block and the sheaves. As a result, it ispossible to keep the strength of the resin blocks high, in spite of theformation of the depression. Therefore, it is possible to allow thestrength and the heat-radiating property of the resin blocks to standtogether at a high level, thereby improving the durability of theV-shaped belt.

According to another aspect of the present invention, there is provideda V-shaped belt comprising a plurality of resin blocks that containscarbon fiber and is arranged in a direction, and an endless connectingmember that extends in the arrangement direction of the resin blocks andthat is impacted into the resin blocks to connect the resin blocks,wherein a depression exposed to air is formed in each resin block.

In one aspect of the present invention, the carbon fiber has a thermalconduction characteristic more excellent than the resin blocks andconsidered that the carbon fiber is added to the resin blocks at thesame time as forming the depressions in the resin blocks. In theV-shaped belt, the heat in the resin blocks can be effectively deliveredto the surface of the resin blocks, that is, the surfaces of thedepressions, through the carbon fiber, thereby improving theheat-radiating property. In addition, since the carbon fiber functionsas a reinforcing material, it is possible to keep the strength of theresin blocks high in spite of the formation of the depressions.Therefore, it is possible to allow the strength and the heat-radiatingproperty of the resin blocks to stand together at a high level, therebyimproving the durability of the V-shaped belt.

According to the present invention described above, it is possible toallow the strength and the heat-radiating property of the resin blocksto stand together, thereby enhancing the durability of the V-shapedbelt. Other features and advantages of the invention will be apparentfrom the following detailed description, taken in conjunction with theaccompanying drawings which illustrate, by way of example, variousfeatures of embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a motor bicycle according to an embodiment ofthe present invention;

FIG. 2 is a side view of a power unit;

FIG. 3 is a cross-sectional view of a belt-type continuously variabletransmission;

FIG. 4 is a side view of a V-shaped belt according to a firstembodiment;

FIG. 5 is a cross-sectional view taken along a line V-V of FIG. 4;

FIG. 6 is an explanatory diagram of a resin block according to the firstembodiment, where FIG. 6( a) is a plan view, FIG. 6( b) is a front view,and FIG. 6( c) is a side view;

FIG. 7 is a schematic diagram illustrating a flow of air in the V-shapedbelt;

FIG. 8 is an explanatory diagram of a resin block according to a secondembodiment, where FIG. 8( a) is a plan view, FIG. 8( b) is a front view,and FIG. 8( c) is a cross-sectional view taken along a line VIIIc-VIIIcof FIG. 10( b);

FIG. 9 is a vertical cross-sectional view of the V-shaped belt accordingto the second embodiment;

FIGS. 10( a)-10(c) are explanatory diagrams of a resin block accordingto a third embodiment, wherein FIG. 10( a) is a plan view, FIG. 10( b)is a front view and FIG. 10( c) is a cross-sectional view taken along aline Xc-Xc of FIG. 10( b);

FIG. 11( a)-11(c) are explanatory diagrams of a resin block according toa fourth embodiment, wherein FIG. 11( a) is a plan view, FIG. 11( b) isa front view and FIG. 11( c) is a cross-sectional view taken along aline XIc-XIc of FIG. 11( b);

FIG. 12( a)-12(c) are explanatory diagrams of a resin block according toa fifth embodiment, wherein FIG. 12( a) is a plan view, FIG. 12( b) is afront view and FIG. 12( c) is a cross-sectional view taken along a lineXIII-XIIc of FIG. 12( b);

FIG. 13 is a longitudinal sectional view of the V-shaped belt accordingto a sixth embodiment;

FIG. 14 is a longitudinal sectional view of the V-shaped belt accordingto a seventh embodiment;

FIG. 15 is a longitudinal sectional view of the V-shaped belt accordingto an eighth embodiment;

FIG. 16 is a longitudinal sectional view of the V-shaped belt accordingto a ninth embodiment;

FIG. 17 is a longitudinal sectional view of the V-shaped belt accordingto a tenth embodiment;

FIG. 18 is a longitudinal sectional view of the V-shaped belt accordingto an eleventh embodiment;

FIG. 19 is a longitudinal sectional view of the V-shaped belt accordingto a twelfth embodiment;

FIG. 20 is a longitudinal sectional view of the V-shaped belt accordingto a thirteenth embodiment.

FIG. 21 is a longitudinal sectional view of the V-shaped belt accordingto another embodiment;

FIG. 22 is a side cross-sectional view of a conventional V-shaped belt;and

FIG. 23 are explanatory diagrams of a conventional resin block, whereinFIG. 23( a) is a plan view, FIG. 23( b) is a front view and FIG. 23( c)is a side view.

DETAILED DESCRIPTION OF THE INVENTION

Now, exemplary embodiments of the present invention will be describedwith reference to the drawings, wherein like numerals refer to likeparts throughout.

FIG. 1 shows a motor bicycle 1 which is an example of a saddle-typevehicle. The motor bicycle 1 has a frame 2. The frame 2 comprises a headsteering pipe 3, a pair of left and right main pipes 4, and a seat rail5 placed on each main pipe 4. The steering head pipe 3 is positioned atthe front end of the frame 2 and supports a front wheel 7 through afront fork 6.

Each main pipe 4 extends backwardly from the steering head pipe 3. Eachmain pipe 4 has a front half portion 4 a extending backward andobliquely downward from the steering head pipe 3, a central portion 4 cextending backward and approximately horizontally from the front halfportion 4 a, and a rear half portion 4 b backward and obliquely upwardfrom the central portion 4 c.

The seat rail 5 is placed across the front half portion 4 a and the rearhalf portion 4 b of the pipe 4. The seat rail 5 supports a seat 8 onwhich a driver rides. The frame 2 is covered with a vehicle cover 9. Thevehicle cover 9 is disposed continuous to the lower end of the seat 8.

A rear arm bracket 10 is fixed to the central portion 4 c of each mainpipe 4. The rear arm bracket 10 is protruded downward from the centralportion 4 c of each main pipe 4. The rear arm bracket 10 supports a reararm 11 extending backward. The rear arm 11 is pivotable upward anddownward on a support point of the rear arm bracket 10. A rear wheel 12is supported by the rear end of the rear arm 11.

The frame 2 supports a power unit 13 for driving the rear wheel 12. Thepower unit 13 includes a 4 cycle single-cylinder engine 14 and abelt-type continuously variable transmission 15 (see FIG. 2). The powerunit 13 is covered with the vehicle cover 9.

The engine 14 is suspended from and supported by the front half portion4 a of the main pipes 4. The engine 14 includes a crank case 16 and acylinder 17 connected to the crank case 16.

The crank case 16 receives a crank shaft 18 and a gear reducer (notshown). As shown in FIG. 3, the crank shaft 18 is supported throughbearings 19 a and 19 b by the crank case 16. The crank shaft 18 ishorizontally disposed along the vehicle-width direction (lateraldirection in FIG. 3) of the motor bicycle 1.

As shown in FIG. 1, an output end of the gear transmission is providedwith a drive sprocket 20. The drive sprocket 20 is disposed in the rearof the crank shaft 18. The center of the rear wheel 12 is provided witha driven sprocket 21. A chain 22 is wound between the drive sprocket 20and the driven sprocket 21.

The cylinder 17 of the engine 14 is protruded upward from the crank case16 along the front half portion 4 a of the main pipes 4. As shown inFIG. 2, the cylinder 17 receives a piston 23. As shown in FIG. 3, thecrank shaft 18 is provided with crank webs 25 a and 25 b. A crank pin 24a is provided between the crank webs 25 a and 25 b. The piston 23 isconnected to the crank pin 24 a through a connecting rod 24.

As shown in FIGS. 2 and 3, The belt-type continuously variabletransmission (hereinafter, referred to as “CVT”) 15 is disposed at theright side of the crank case 16. The right side surface of the crankcase 16 is covered with a transmission case 28 and the CVT 15 isreceived in the transmission case 28.

The CVT 15 comprises a primary sheave 29, a secondary sheave 30, and aV-shaped belt 31 wound on the primary sheave 29 and the secondary sheave30. The primary sheave 29 is positioned at the front side in thetransmission case 28 and is supported by an input shaft 32. As shown inFIG. 3, the input shaft 32 is integrally formed with the crank shaft 18.A journal portion 18 a positioned at the right end of the crank shaft 18extends to right toward the transmission case 28 (not shown in FIG. 3).The extending portion also serves as the input shaft 32.

The primary sheave 29 includes a fixed plate 34 a and a sliding plate 34b opposed to the fixed plate 34 a. The fixed plate 34 a is fixed to theend of the input shaft 32. Accordingly, the fixed plate 34 a rotatesintegrally with the input shaft 32. On the other hand, the sliding plate34 b is slidable in the axis direction of the input shaft 32. Thesliding plate 34 b has a cylinder-shaped boss portion 35. The bossportion 35 is supported through a collar 36 by the input shaft 32. As aresult, the sliding plate 34 b is slidable in the direction in which thesliding plate 34 b moves closer to or apart from the fixed plate 34 aand is rotatable about the input shaft 32.

The primary sheave 29 has a pair of sandwiching surfaces 37 a and 37 bbetween which the V-shaped belt 31 is sandwiched. Specifically, thesandwiching surface 37 a is formed at the left side of the fixed plate34 a and the sandwiching surface 37 b is formed at the right side of thesliding plate 34 b. The sandwiching surfaces 37 a and 37 b are formed ina cone shape and are opposed to each other. The sandwiching surfaces 37a and 37 b define a belt groove 38 having a V-shaped section between thefixed plate 34 a and the sliding plate 34 b. The width L1 of the beltgroove 38 can be adjusted by means of sliding of the sliding plate 34 b.

A cam plate 39 is fixed to the left outer circumferential portion of theinput shaft 32. Therefore, the cam plate 39 rotates along with the inputshaft 32. The cam plate 39 is opposed to the sliding plate 34 b in thelateral direction. The sliding plate 34 b is mounted to the cam plate 39and is slidable in the axis direction of the input shaft 32. As aresult, the cam plate 39 and the sliding plate 34 b are movable in thedirection in which they get closer to or apart from each other whilerotating together.

A cam surface 40 opposed to the cam plate 39 is formed at the left sideof the sliding plate 34 b. A plurality of weight rollers 41 is providedbetween the sliding plate 34 b and the cam plate 39 (only one weightroller 41 is shown in FIG. 3). When the crank shaft 18 rotates, acentrifugal force is generated in the weight roller 41. The weightroller 41 moves along the cam surface 40 in response to the centrifugalforce. By means of the movement, a force to the right side is applied tothe sliding plate 34 b from the weight roller 41, and thus the slidingplate 34 b slides in the axis direction of the input shaft 32. As aresult, the width L1 of the belt groove 38 varies.

The secondary sheave 30 is disposed at the rear side in the transmissioncase 28. The secondary sheave 30 is supported by an output shaft 42. Theoutput shaft 42 is disposed parallel to the input shaft 32 and isconnected to an input end of the gear reducer through an automaticcentrifugal clutch (not shown).

The secondary sheave 30 has a fixed plate 45 a and a sliding plate 45 b.The rotation center of the fixed plate 45 a is provided with acylinder-shaped collar 46. The collar 46 engages with the outercircumferential surface of the output shaft 42. By means of theengagement, the fixed plate 45 a and the output shaft 42 rotatetogether.

The rotation center of the sliding plate 45 b is provided with a sleeve47. The sleeve 47 is fitted onto the outer circumferential surface ofthe collar 46 to be slidable in the axis direction thereof. A pluralityof engaging grooves 48 is formed in the sleeve 47. The engaging grooves48 extend in the axis direction of the sleeve 47 and are arranged in thecircumferential direction of the sleeve 47 with a separation.

The collar 46 has a plurality of engaging pins 49. The engaging pins 49are protruded in the outward radial direction of the collar 46 and areslidably impacted into the engaging grooves 48 of the sleeve 47. As aresult, the fixed plate 45 a and the sliding plate 45 b rotate togetherand are movable in the direction in which they get closer to or apartfrom each other.

The secondary sheave 30 has a pair of sandwiching surfaces 51 a and 51 bbetween where the V-shaped belt 31 is sandwiched. Specifically, thesandwiching surface 51 a is formed at the right side of the fixed plate45 a and the sandwiching surface 51 b is formed at the left side of thesliding plate 45 b. The sandwiching surfaces 51 a and 51 b are formed ina cone shape and are opposed to each other. The sandwiching surfaces 51a and 51 b define a belt groove 52 having a V-shaped section between thefixed plate 45 a and the sliding plate 45 b. The width L2 of the beltgroove 52 can be adjusted by means of sliding of the sliding plate 45 b.

A spring bearing 53 is fixed to the right end of the collar 46. Thespring bearing 53 is laterally opposed to the sliding plate 45 b. Acompression coil spring 54 is disposed between the spring bearing 53 andthe sliding plate 45 b. The spring 54 biases the sliding plate 45 btoward the fixed plate 45 a.

As shown in FIG. 3, the V-shaped belt 31 is wound around the primarysheave 29 and the secondary sheave 30. Specifically, the V-shaped belt31 is impacted into the belt groove 38 of the primary sheave 29 and thebelt groove 52 of the secondary sheave 30. The detailed construction ofthe V-shaped belt 31 will be described in greater detail herein below.

In a state where the number of rotation of the crank shaft 18 is small(for example, in a state where the engine 14 is under idling or thelike), the centrifugal force acting on the weight roller 41 is small.Accordingly, the weight roller 41 is positioned at the inner radial sideof the primary sheave 29. In this state, the sliding plate 34 b is mostapart from the fixed plate 34 a, and the width L1 of the belt groove 38is the maximum. As a result, the winding diameter of the V-shaped belt31 in the primary sheave 29 is the minimum.

On the contrary, in the secondary sheave 30, the sliding plate 45 b isbiased toward the fixed plate 45 a by the spring 54, and thus the beltwidth L2 is the minimum. As a result, the V-shaped belt 31 impacted intothe belt groove 52 is extruded toward the outer circumferential portionof the secondary sheave 30. Consequently, the winding diameter of theV-shaped belt 31 in the secondary sheave 30 is the maximum.

In this way, in the state where the number of rotation of the crankshaft 18 is small, the winding diameter in the primary sheave 29 is theminimum and the winding diameter in the secondary sheave 30 is themaximum. As a result, the transmission ratio of the CVT 15 is themaximum.

On the other hand, when the number of rotation of the crank shaft 18 isincreased, the centrifugal force acting on the weight roller 41 isincreased, and thus the weight roller 41 moves in the outward radialdirection of the sliding plate 34 b. As a result, the sliding plate 34 bis pressed to right side by the weight roller 41 and slides toward thefixed plate 34 a. Consequently, the width L1 of the belt groove 38becomes smaller slowly. Then, the V-shaped belt 31 sandwiched betweenthe sandwiching surfaces 37 a and 37 b is extruded in the outward radialdirection of the primary sheave 29, and thus the winding diameter of theV-shaped belt 31 in the primary sheave 29 is increased.

On the contrary, in the secondary sheave 30, the V-shaped belt 31 ispulled in the inward radial direction of the secondary sheave 30 to betight, with increase in winding diameter in the primary sheave 29.Accordingly, the force acting to the right side is given to the slidingplate 45 b from the V-shaped belt 31, and thus the sliding plate 45 bslides against the biasing force of the spring 54 in the direction inwhich the sliding plate 45 b gets apart from the fixed plate 45 a. As aresult, the width L2 of the belt groove 38 becomes greater slowly.Consequently, the winding diameter of the V-shaped belt 31 in thesecondary sheave 30 is decreased.

In this way, when the number of rotation of the crank shaft 18 isincreased, the winding diameter in the primary sheave 29 is increased,and the winding diameter in the secondary sheave 30 is decreased.Accordingly, in the CVT 15 described hitherto, the transmission ratiovaries automatically and continuously with the increase in the number ofrotation of the crank shaft 18. In addition, the transmission ratio ofthe CVT 15 is the minimum when the winding diameter in the primarysheave 29 is the maximum.

Next, the detailed construction of the V-shaped belt 31. As shown inFIGS. 4 and 5, the V-shaped belt 31 comprises a plurality of resinblocks 56 a arranged in a direction and a pair of connecting members 57for connecting the resin blocks 56 a. In the following description, thelongitudinal direction, the lateral direction, and the verticaldirection of the resin blocks 56 a are defined as follows for thepurpose of convenient explanation. That is, the longitudinal directiondenotes the arrangement direction of the resin blocks 56 a. The surfacesof the resin blocks 56 a contacting the sheaves 29 and 30 are denoted bylateral surfaces. The portion positioned at the outside in the diameterdirection of the sheaves 29 and 30 when the V-shaped belt 31 is woundedaround the sheaves 29 and 30 is referred to as an upper portion, and theportion positioned at the inside in the diameter direction is referredto as a lower portion. However, the respective directions describedabove are, in one aspect, defined for the purpose of convenientexplanation and do not necessarily refer to the directions when theV-shaped belt is in use.

As shown in FIGS. 6( a) to 6(c), each resin block 56 a is made of a thinplate having a small longitudinal width and has both lateral surfaces70, an upper surface 71, and a lower surface 72. As shown in FIG. 6( b),the lateral length of the resin block 56 a is decreased from the uppersurface 71 to the lower surface 72, and the resin block 56 a is formedto correspond to the V shape of the belt grooves 38 and 52 of thesheaves 29 and 30. Grooves 59 are recessed inward in the verticalcenters of both lateral surfaces 70 of the resin block 56 a. The grooves59 are used to impact the connecting members 57 thereto. In the statewhere the connecting members 57 are impacted into the resin block 56 a,the groove 59 is not exposed to the air.

On the other hand, depressions 81 and 82 exposed to the air are formedin the upper surface 71 and the lower surface 72 of the resin block 56a. The depressions 81 and 82 are formed from both laterals to the centerof the resin block 56 a and recessed in the longitudinal direction (seeFIG. 6( a)). The depressions 81 and 82 are formed in the front surfaceand the rear surface of the resin block 56 a, respectively. Thelongitudinal widths of the upper portion and the lower portion of theresin block 56 a are gradually decreased from both laterals to thecenter. However, the depressions 81 and 82 are formed at the centerrather than at both laterals and are not formed at both laterals.Therefore, only both laterals of the resin block 56 a, that is, theportions contacting the sheaves 29 and 30, have a width greater thanother portions by a width which the depressions are not formed.

In addition, as shown in FIG. 6( b), the depressions 81 and 82 arevertically recessed from both laterals of the resin block 56 a to thecenter. That is, the depressions 81 and 82 are recessed longitudinallyand vertically. The depressions 81 and 82 are inwardly recessed in thelateral section of the resin block 56 a (the section perpendicular tothe arrangement direction of the resin block 56 a). In one embodiment,the degree of recession is increased from both laterals of the resinblock 56 a to the center and the depressions 81 and 82 are most greatlyrecessed at the lateral center.

As shown in FIG. 6( c), the upper end and the lower end of the resinblock 56 a in which the depressions 81 and 82 are formed is taperedtoward both ends. In one embodiment, in the longitudinal sectionincluding the depressions 81 and 82 (the section vertically parallel tothe arrangement direction of the resin blocks 56 a), the outline of theends of the resin block 56 a is curved. The shape of the outline is notparticularly limited and is formed preferably in a quadratic curve suchas parabola. The protruded end of the resin block 56 a has a curvedsurface.

The resin blocks 56 a have a base material made of resin and areinforcing material. In one embodiment, carbon fiber is contained asthe reinforcing material in the resin blocks 56 a. The carbon fiber hasthermal conductivity that is generally better than the resin material ofthe base material. The carbon fiber contained in the resin blocks 56 aperforms a function of enhancing the thermal conductivity of the resinblocks 56 a, as well as a function as the reinforcing material. The heatradiating property of the resin blocks 56 a can be improved with anincrease in content of the carbon fiber. The content of the carbon fibercan be properly set in consideration of a desired strength orproductivity of the resin blocks 56 a.

In one aspect, when a sufficient strength can be realized, thereinforcing material may be omitted. In some cases, materials other thanthe reinforcing material may be contained in the base material. Variousresin materials such as thermoplastic resin, thermosetting resin, andthe like can be used as the base material. The kind of the reinforcingmaterial is not limited and may properly employ glass fiber, aramidfiber, or the like, in addition to the carbon fiber. For example, a wearpreventing agent or frictional-coefficient adjusting agent may becontained in the material other than the reinforcing material.

In one embodiment, the connecting member 57 is formed endless. As shownin FIG. 4, the connecting member 57 extends the arrangement direction ofthe resin blocks 56 a and is impacted into the grooves 59 of the resinblocks 56 a. In this way, by impacting the connecting member 57 into thegrooves 59 of the resin blocks 56 a, a plurality of resin blocks 56 aare connected to each other through the connecting member 57. In oneembodiment, the connecting member 57 can be formed of rubber. The kindof the rubber constituting the connecting member 57 is not particularlylimited and, for example, super heat-proof rubber may be most preferablyused. As shown in FIG. 5, a plurality of cores 60 for reinforcement canbe buried in the rubber.

The resin blocks 56 a and the connecting member 57 are not integrallyvulcanized. However, the resin blocks 56 a and the connecting member 57may be integrally vulcanized.

As described hitherto, in the V-shaped belt 31 according to oneembodiment, the depressions 81 and 82 exposed to the air are formed inthe upper side and the lower side of the resin blocks 56 a,respectively. As a result, the heat-radiating area of the resin blocks56 a is enlarged. That is, the area of the resin blocks 56 a contactingthe air is enlarged. Therefore, the heat-radiating property of the resinblocks 56 a is improved.

As schematically shown in FIG. 7, since the depressions 81 and 82 (thedepression 82 is not shown in FIG. 7) are formed in the front surfaceand the rear surface of each resin block 56 a, clearances 83 are formedbetween the neighboring resin blocks 56 a. As a result, the air flows inthe clearances 83 with the traveling of the V-shaped belt 31 (see thesolid arrows in FIG. 7). Specifically, the clearances 83 are formed inthe traveling direction of the V-shaped belt 31 (the traveling directionis parallel to the arrangement direction of the resin blocks 56 a). Theclearances 83 are formed at the front side of the respective resinblocks 56 a in the traveling direction. Therefore, since the clearances83 are formed in the portions in which the air can easily flow, the airactively flows over the surfaces of the resin blocks 56 a with thetraveling of the V-shaped belt 31, thereby further improving theheat-radiating property of the resin blocks 56 a.

When the number of rotation of the sheaves 29 and 30 is increased, theamount of heat emitted from the V-shaped belt 31 is increased. However,according to one embodiment, the traveling speed of the V-shaped belt 31is increased with increase in the number of rotation of the sheaves 29and 30, and thus the flow rate of the air passing through the clearances83 is increased. As a result, the increase in the number of rotation ofthe sheaves 29 and 30 improves the heat-radiating property of the resinblocks 56 a. Therefore, according to one embodiment, it is possible toprevent an increase in temperature of the V-shaped belt 31 even in thecase of high-speed driving.

In the V-shaped belt 31 according to one embodiment, the upper end andthe lower end in the longitudinal section of the each resin block 56 aincluding the depressions 81 and 82 are tapered. As a result, theclearance 83 is formed in a shape of which the end is widened toward theopening end, thereby easily introducing air. Therefore, it is possibleto further improve the heat-radiating property of the V-shaped belt 31.

In the V-shaped belt 31 according to one embodiment, the outline of theend in the longitudinal section of each resin block 56 a is in a curvedline. As a result, since the air can smoothly flow in the clearances 83along the curved lines of the resin blocks 56 a. That is, the protrudedend of each resin block 56 a has a curved surface and the protruded isrounded, the air can smoothly flow in the clearance 83. Therefore, it ispossible to more efficiently accomplish the heat-radiation.

In one aspect, the depressions 81 and 82 are formed at the lateralcenter of each resin block 56 a. As a result, the center at which heatcan most easily stay in each resin block 56 a can be efficiently cooled.

In the V-shaped belt 31 according to one embodiment, since the resinblocks 56 a have an excellent heat-radiating property; heat difficultystays in the resin blocks 56 a. As a result, it is possible to preventthe excessive increase in temperature of the resin blocks 56 a and theconnecting member 57. In addition, since the heat-proof characteristicof the V-shaped belt 31 is improved, it is possible enhance thereliability of the V-shaped belt 31.

In the V-shaped belt 31 according to one embodiment, the depressions 81and 82 are formed at the center side rather than both laterals of eachresin block 56 a. In other words, the depressions 81 and 82 are formedin the portions other than both laterals and are separated from bothlateral surfaces 70 of each resin block 56 a. As a result, although thedepressions 81 and 82 are provided, the area of the contact portions ofthe resin blocks 56 a with the sheaves 29 and 30 can be sufficientlyguaranteed, and thus the strength of the contact portions can be keptwell.

In addition, in the V-shaped belt 31 according to one embodiment, thedepressions 81 and 82 do not reach the connecting member 57 but areseparated from the connecting member 57. In other words, the depressions81 and 82 are formed in the portions into which the connecting member 57is not impacted. As a result, although the depressions 81 and 82 areprovided, the strength of the engaging portions of the resin blocks 56 awith the connecting member 57 cannot be decreased greatly. Therefore, itis possible to maintain the high strength of the resin blocks 56 a.

In one aspect, the carbon fiber is contained in the resin blocks 56 a ofthe V-shaped belt 31. As a result, the heat in the resin blocks 56 a canbe delivered to the surfaces of the resin blocks 56 a (specifically, thesurfaces of the depressions 81 and 82 with a high cooling effect)through the carbon fiber, thereby further improving the heat-radiatingproperty. In addition, since the carbon fiber functions as thereinforcing material, it is possible to maintain the high strength ofthe resin blocks 56 a in spite of the depressions 81 and 82.

In the V-shaped belt 31 according to one embodiment, it is possible forthe strength and the heat-radiating property of the resin blocks 56 a tostand together at a high level. Therefore, it is possible to improve thedurability of the V-shaped belt 31.

According to one embodiment, since the deterioration of the V-shapedbelt 31 due to the heat emission can be suppressed, it is possible toimprove the reliability of the CVT 15. In addition, since the V-shapedbelt 31 is not deteriorated easily even at the time of high-speeddriving, it is possible to enlarge the allowable operation range of theCVT 15. The improvement of the reliability of the CVT 15 also improvesthe reliability of the motor bicycle 1. The enlargement of the allowableoperation range of the CVT 15 can improve the degree of freedom indesigning the engine 14.

Next, a V-shaped belt 31 according to other embodiments of the presentinvention will be described. In the embodiments described below, theV-shaped belt 31 comprises a plurality of resin blocks and a connectingmember. Since the connecting member is similar to the first embodiment,description thereof will be omitted. Hereinafter, the resin blocks aredescribed mainly. The same elements as the first embodiment are denotedby the same reference numerals and description thereof will be omitted.

FIGS. 8( a) to 8(c) show a resin block 56 b of the V-shaped belt 31according to a second embodiment. Similarly to the resin block 56 aaccording to the first embodiment, depression 81 is formed in the upperfront and rear surfaces of the resin block 56 b and depression 82 isformed in the lower front and rear surfaces of the resin block 56 baccording to the second embodiment. However, the depressions 81 and 82of the resin block 56 b are recessed in a step shape, and thus a stepdifference is formed in the boundaries of the depressions 81 and 82.

As shown in FIG. 8( a), the longitudinal width of the resin block 56 bis decreased from both lateral ends to the center step-like. Thelongitudinal width of the depression 81 is constant. As shown in FIG. 8(b), the upper depression 81 is vertically recessed toward the center ofthe resin block 56 b. In one aspect, the vertical length of thedepression 81 is constant almost all over the lateral direction and thebottom side of the depression 81 is parallel to the upper surface 71 ofthe resin block 56 b. The lower depression 82 is also verticallyrecessed to the center of the resin block 56 b. The vertical length ofthe depression 82 is constant almost all over the lateral direction. Asshown in FIG. 8( c), the upper portion and the lower portion of theresin block 56 b has a width smaller than that of the vertical center.

Therefore, as shown in FIG. 9, in the V-shaped belt 31 according to thesecond embodiment, the heat-radiating area of the resin blocks 56 b isenlarged and clearances 83 are formed between the neighboring resinblocks 56 b. As a result, the heat-radiating property of the resinblocks 56 b can be improved, and the heat can be prevented from stayingin the resin blocks 56 b. Therefore, it is possible to suppress thedeterioration of the V-shaped belt 31 due to the generation of heat.FIG. 9 is a longitudinal sectional view of the V-shaped belt 31including the depressions 81 and 82, where the hatching marks indicatinga section are omitted. The same is true of all the following figures.

FIGS. 10( a) to 10(c) show a resin block 56 c of a V-shaped belt 31according to a third embodiment. Two depressions 81 laterally arrangedare formed in each of the upper front and rear surfaces of the resinblock 56 c. A depression 82 is formed in each of the lower front andrear surfaces. Similar to the second embodiment, the depressions 81 and82 are recessed in a step shape in the resin block according to thethird embodiment, and thus a step can be formed in each boundary of thedepressions 81 and 82.

As shown in FIG. 10( a), the longitudinal width of the resin block 56 cis step-like decreased from both laterals to the center and is step-likeincreased at the center. The longitudinal width in the depression 81 isconstant. As shown in FIG. 10( b), the upper depressions 81 are recesseddownwardly. In one aspect, the vertical length of the depressions 81 isconstant almost all over the lateral direction, and the bottom side ofthe depressions 81 is parallel to the top surface 71 of the resin block56 c. As shown in FIG. 10( c), the upper end and the lower end of theresin block 56 c have a width smaller than the vertical center.

Therefore, in the V-shaped belt 31 according to the third embodiment,the heat-radiating area of the resin blocks 56 c can be enlarged andclearances can be formed between the neighboring resin blocks 56 c. As aresult, the heat-radiating property of the resin blocks 56 c isimproved, and thus the deterioration of the V-shaped belt 31 due to thegeneration of heat can be suppressed.

FIGS. 11( a) to 11(c) show a resin block 56 d of the V-shaped belt 31according to a fourth embodiment. In the resin block 56 d according tothe fourth embodiment, a depression 81 is formed in the upper front andrear surfaces and a depression 82 is formed in the lower front and rearsurfaces. A depression 84 connecting the upper depression 81 to thelower depression 82 is formed at the center of the resin block 56 d. Acircumferential portion 85 extending approximately vertically is formedat both sides of the depression 84. In the resin block 56 d according tothe fourth embodiment 4, since the depressions 81, 82, and 84 arevertically connected to each other, an approximately I-shaped depressionvertically extending in the resin block 56 d as a whole is formed. Otherconstruction is similar to the resin block 56 d according to the secondembodiment.

Therefore, in the V-shaped belt 31 according to the fourth embodiment,the heat-radiating property of the resin blocks 56 d can be improved tothereby suppress the deterioration due to the generation of heat. Inaddition, in the fourth embodiment, since the depression 84 is formed atthe vertical center of each resin block 56 d, it is possible toefficiently cool the center of the resin blocks 56 d. Heat can mosteasily stay at the center of the resin blocks 56 d. Therefore, accordingto the fourth embodiment, since the portion in which the heat easilystays can be directly cooled, it is possible to further improve theheat-radiating property of the resin blocks 56 d. Therefore, it ispossible to further suppress the deterioration of the V-shaped belt 31due to the generation of heat.

FIGS. 12( a) to 12(c) show a resin block 56 e of the V-shaped belt 31according to a fifth embodiment. The resin block 56 e is obtained byremoving the circumferential portion 85 of the center depression 84 fromthe resin block 56 d according to the fourth embodiment. Therefore, inthe fifth embodiment, since the center portion in which the heat caneasily stay can be directly cooled, thereby improving the heat-radiatingproperty of the resin block 56 d.

In the second to fifth embodiments described hitherto, the longitudinalwidths in the upper end and the lower end of the resin blocks 56 b to 56d are constant. However, the shapes of the ends of the resin blocks 56 bto 56 d are not limited. For example, the ends of the resin blocks 56 bto 56 d may be formed tapered. Next, embodiments in which the end shapesof the resin blocks 56 b to 56 d are modified will be described.

FIG. 13 shows a V-shaped belt 31 according to a sixth embodiment. In thesixth embodiment, the upper and lower ends of the resin blocks 56 e havethe front and rear edges obliquely cut out. That is, the ends are in achamfered shape. As a result, in the sixth embodiment, the clearances 83formed between the neighboring resin blocks 56 e is widened toward theopening end (in other words, the exit and entrance side of the air).

In the V-shaped belt 31 according to the sixth embodiment, since theopening end of the clearances 83 is widened, the air can easily enterthe clearances 83. As a result, it is possible to further improve theheat-radiating property of the resin blocks 56 e.

FIG. 14 shows a V-shaped belt 31 according to a seventh embodiment. Inthe seventh embodiment, the upper and lower ends of the resin blocks 56f have the front and rear edges obliquely cut out. However, in theseventh embodiment, the edges are in a shape longitudinally cut out fromthe longitudinal center position thereof. Therefore, the ends of theresin blocks 56 f have a pointed shape with an acute angle.

According to the seventh embodiment, since the opening end of theclearances 83 is widened, the air can easily enter the clearances 83. Asa result, it is possible to improve the heat-radiating property of theresin blocks 56 f.

FIG. 15 shows a V-shaped belt 31 according to an eighth embodiment. Inthe eighth embodiment, the upper and lower ends of the resin blocks 56 ghave a sectional shape of a circular arc. As a result, the width of theclearances 83 varies continuously and slowly. Accordingly, since thearea of a flow path in the clearances 83 is not rapidly changed, the aircan be smoothly introduced into the clearances 83. Therefore, it ispossible to improve the heat-radiating property of the resin blocks 56g.

In the sixth to eighth embodiments, only the ends of the resin blocks 56e to 56 f have a partially narrowed tip. However, the entire portions ofthe resin blocks from the vertical center to the ends may be formed tohave a narrowed tip. Next, embodiments in which the entire portion fromthe center to the ends of the resin block is formed to have a slowlynarrowed tip will be described.

FIG. 16 shows a V-shaped belt 31 according to a ninth embodiment. In theninth embodiment, the upper and lower ends of a resin block 56 h areformed in a shape that the entire portions from the center to the endsare obliquely cut out. As a result, the width of the clearances 83 isslowly widened from the center to the ends. Therefore, since the air caneasily flow in the clearances 83, it is possible to improve theheat-radiating property of the resin blocks 56 h.

FIG. 17 shows a V-shaped belt 31 according to a tenth embodiment. Aresin block 56 i according to the tenth embodiment has a shape that theends of the resin block 56 h according to the ninth embodiment arefurther chamfered. In other words, the resin block 56 i has a shape thatthe ends are narrowed in two steps from the center to the ends.According to the tenth embodiment, since the entrance of the clearances83 is further widened, the air can more easily flow in the clearances83. Therefore, it is possible to improve the heat-radiating property ofthe resin blocks 56 i.

FIG. 18 shows a V-shaped belt 31 according to an eleventh embodiment. Aresin block 56 j according to the eleventh embodiment has a shape thatthe ends are narrowed in two steps from the center to the ends. However,in the eleventh embodiment, the ends are formed in a pointed shape withan acute angle. According to the eleventh embodiment, since the entranceof the clearances 83 is widened, the air can more easily flow in theclearances 83. Therefore, it is possible to improve the heat-radiatingproperty of the resin blocks 56 j.

FIG. 19 shows a V-shaped belt 31 according to a twelfth embodiment. Aresin block 56 k according to the twelfth embodiment has a shape thatthe edges are cut out from the center to the ends into a tapered shapewith an acute angle. According to the twelfth embodiment, since theentrance of the clearances 83 is further widened, the air can moreeasily flow in the clearances 83. Therefore, it is possible to improvethe heat-radiating property of the resin blocks 56 k.

FIG. 20 shows a V-shaped belt 31 according to a thirteenth embodiment.In the thirteenth embodiment, the sectional shape of the resin blocksaccording to the second to fifth embodiments is changed to the sameshape as the first embodiment. That is, in the thirteenth embodiment,the longitudinal width of a resin block 56 l is smoothly decreased fromthe center to the ends. The outline of the ends of the resin block 56 lforms a convex curve toward the tip. According to the thirteenthembodiment, as described in the first embodiment, the air can smoothlyflow in the clearances 83 along the curved shape of the resin block 56l. As a result, since the air can easily flow in the clearances 83, itis possible to improve the heat-radiating property of the resin blocks56 l.

As described above, by continuously or step-like reducing the width ofthe resin block from the center to the ends in the longitudinal sectionof the resin block, the clearances can be formed between the neighboringresin blocks so as to be widened from the center to the ends of theresin blocks. As a result, since the air can easily flow in theclearances, it is possible to effectively improve the heat-radiatingproperty of the resin blocks.

The V-shaped belt according to the present invention is not limited tothe above-mentioned embodiments but may be embodied in various forms. Inthe embodiments, the depressions 81 and 82 are formed in all the resinblocks. However, the depressions 81 and 82 may be formed in only a partof the resin blocks. That is, in a part of the V-shaped belt, aplurality of resin blocks in which the depressions 81 and 82 are formedmay be connected through the connecting member. Therefore, the V-shapedbelts obtained by combining the resin blocks having the depressions 81and 82 and the resin blocks having no depression belong to the scope ofthe present invention. By preparing plural kinds of resin blocks inwhich depressions having different shapes and sizes are formed andcombining these resin blocks of different kinds, it is also possible toconstitute a V-shaped belt 31.

For example, as shown in FIG. 21, first resin blocks 56 m having thedepressions and resin blocks 56 n having no depression may bealternately arranged in the length direction of the connecting member57. Such a V-shaped belt 31 can improve the heat-radiating property. Ina V-shaped belt in which a plurality of resin blocks are generallyconnected to each other, when the connecting member is loosened,high-frequency vibration may occur in the V-shaped belt. However, in theV-shaped belt described above, since the resin blocks 56 m having thedepressions and the resin blocks 56 n having no depression are mixed,the resonant frequency can be dispersed. Therefore, it is possible tosuppress the vibration and noises of the V-shaped belt 31. In addition,even when plural kinds of resin blocks having the depressions are formedat different positions or plural kinds of resin blocks having thedepressions formed in different shapes or sizes are combined, it ispossible to reduce the vibration and noises, similarly to the V-shapedbelt 31 shown in FIG. 21.

As described above, various embodiments of the present invention areapplicable to a V-shaped belt, a belt-type transmission having theV-shaped belt, and a saddle-type vehicle.

While the description above refers to particular embodiments of thepresent invention, it will be understood that many modifications may bemade without departing from the spirit thereof. The accompanying claimsare intended to cover such modifications as would fall within the truescope and spirit of the present invention.

The presently disclosed embodiments are therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims, rather than theforegoing description, and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

1. A V-shaped belt comprising: a plurality of resin blocks each havingfirst and second longitudinal surfaces, and first and second lateralsurfaces arranged to engage inner surfaces of a sheave, the plurality ofresin blocks arranged side-by-side in a longitudinal direction of theplurality of resin blocks; and an endless connecting member extending inthe longitudinal direction of the plurality of resin blocks and impactedinto the plurality of resin blocks to connect the plurality of resinblocks to each other; wherein each of the plurality of resin blocksinclude: a depression provided at a center of each of the first andsecond longitudinal surfaces and spaced inwardly from the first andsecond lateral surfaces, the depressions are exposed to air; and carbonfibers arranged adjacent to or at a surface of the depressions so as toconduct heat from the plurality of resin blocks directly to the surfaceof the depressions.
 2. A V-shaped belt comprising: a plurality of resinblocks each having first and second longitudinal surfaces, and first andsecond lateral surfaces arranged to engage inner surfaces of a sheave,the plurality of resin blocks arranged side-by-side in a longitudinaldirection of the plurality of resin blocks; and an endless connectingmember extending in the longitudinal direction of the plurality of resinblocks and impacted into the plurality of resin blocks to connect theplurality of resin blocks to each other; wherein each of the pluralityof resin blocks include: a depression provided at a center of each ofthe first and second longitudinal surfaces and spaced inwardly from thefirst and second lateral surfaces, the depressions are exposed to air;and the first and second lateral surfaces extend upwards to a point thatis located below tops of the plurality of resin blocks and correspondsto a maximum longitudinal width of the plurality of resin blocks;wherein the depressions extend from the tops of the plurality of resinblocks to a point below the point to which the first and lateralsurfaces extend upwards.
 3. The V-shaped belt according to claim 2,further comprising: a bottom depression provided at the center of eachof the first and second longitudinal surfaces and spaced inward from thefirst and second lateral surfaces, the bottom depressions being exposedto air; wherein the first and second lateral surfaces extend from alower point above bottoms of the plurality of resin blocks; and thebottom depressions in the first and second longitudinal surfaces extendfrom the bottoms of the plurality of resin blocks to a point above thelower point of the first and lateral surfaces.
 4. A V-shaped beltcomprising: a plurality of resin blocks each having first and secondlongitudinal surfaces, and first and second lateral surfaces arranged toengage inner surfaces of a sheave, the plurality of resin blocksarranged side-by-side in a longitudinal direction of the plurality ofresin blocks; and an endless connecting member extending in thelongitudinal direction of the plurality of resin blocks and impactedinto the plurality of resin blocks to connect the resin blocks to eachother; wherein each of the plurality of resin blocks include: adepression provided at a center of each of the first and secondlongitudinal surfaces and spaced inwardly from the first and secondlateral surfaces, the depressions are exposed to air; and first andsecond grooves extending inwards from the first and second lateralsurfaces, the endless connecting member arranged within the first andsecond grooves, and inner portions of the first and second groovesangling inward so as to meet at a single point that defines an innermostpoint of the first and second grooves.
 5. A V-shaped belt comprising: aplurality of resin blocks each having first and second longitudinalsurfaces and first and second lateral surfaces arranged to engage innersurfaces of a sheave, the plurality of resin blocks arrangedside-by-side in a longitudinal direction of the plurality of resinblocks; and an endless connecting member extending in the longitudinaldirection of the plurality of resin blocks and impacted into theplurality of resin blocks to connect the plurality of resin blocks toeach other; wherein each of the plurality of resin blocks include: adepression provided at a center of each of the first and secondlongitudinal surfaces and spaced inwardly from the first and secondlateral surfaces, the depressions are exposed to air; wherein across-sectional shape of a top of each of the plurality of resin blocksalong the center of the first and second longitudinal surfaces is curvedsuch that air can smoothly flow from the depression on the firstlongitudinal surface over the top of each of the plurality of resinblocks to the depression on the second longitudinal surface.
 6. AV-shaped belt comprising: a plurality of resin blocks each having firstand second longitudinal surfaces, and first and second lateral surfacesarranged to engage inner surfaces of a sheave, the plurality of resinblocks arranged side-by-side and abutting each other in a longitudinaldirection of the plurality of resin blocks; and an endless connectingmember extending in the longitudinal direction of the plurality of resinblocks and impacted into the plurality of resin blocks to connect theplurality of resin blocks to each other; wherein each of the pluralityof resin blocks include: a depression provided at a center of each ofthe first and second longitudinal surfaces and spaced inwardly from thefirst and second lateral surfaces, the depressions are exposed to air;and carbon fibers arranged to conduct heat from the plurality of resinblocks to a surface of the depressions.